Abstract:To mitigate shock forces in collision events, thin-walled members are used as energy absorber. In this article, crashworthiness of single-cell and multi-cell S-shaped members with various crosssections including triangular, square, hexagonal, decagon and circular were investigated under axial dynamic loading using finite element code LS-DYNA. Furthermore, crashworthiness of the S-rails with the same outer tubes and different inner ones was studied as well. The multi-cell members employed in this task were doub… Show more
“…Welding processes are evaluated using MCDM with fuzzy logic [29], while laser cutting technological parameters are defined using AHP-TOPSIS [30]. There are many methods for thin-walled structure evaluation using Complex Proportional Assessment (COPRAS) [31][32][33][34][35][36][37], which confirms the implementation of these methods in the field of engineering.…”
Steel ropes are complex flexible structures used in many technical applications, such as elevators, cable cars, and funicular cabs. Due to the specific design and critical safety requirements, diagnostics of ropes remains an important issue. Broken wire number in the steel ropes is limited by safety standards when they are used in the human lifting and carrying installations. There are some practical issues on loose wires-firstly, it shows end of lifetime of the entire rope, independently of wear, lubrication or wrong winding on the drums or through pulleys; and, secondly, it can stick in the tight pulley-support gaps and cause deterioration of rope structure up to birdcage formations. Normal rope operation should not generate broken wires, so increasing of their number shows a need for rope installation maintenance. This paper presents a methodology of steel rope diagnostics and the results of analysis using multi-criteria analysis methods. The experimental part of the research was performed using an original test bench to detect broken wires on the rope surface by its vibrations. Diagnostics was performed in the range of frequencies from 60 to 560 Hz with a pitch of 50 Hz. The obtained amplitudes of the broken rope wire vibrations, different from the entire rope surface vibration parameters, was the significant outcome. Later analysis of the obtained experimental results revealed the most significant values of the diagnostic parameters. The evaluation of the power of the diagnostics was implemented by using multi-criteria decision-making (MCDM) methods. Various decision-making methods are necessary due to unknown efficiencies with respect to the physical phenomena of the evaluated processes. The significance of the methods was evaluated using objective methods from the structure of the presented data. Some of these methods were proposed by authors of this paper. Implementation of MCDM in diagnostic data analysis and definition of the diagnostic parameters significance offers meaningful results.
“…Welding processes are evaluated using MCDM with fuzzy logic [29], while laser cutting technological parameters are defined using AHP-TOPSIS [30]. There are many methods for thin-walled structure evaluation using Complex Proportional Assessment (COPRAS) [31][32][33][34][35][36][37], which confirms the implementation of these methods in the field of engineering.…”
Steel ropes are complex flexible structures used in many technical applications, such as elevators, cable cars, and funicular cabs. Due to the specific design and critical safety requirements, diagnostics of ropes remains an important issue. Broken wire number in the steel ropes is limited by safety standards when they are used in the human lifting and carrying installations. There are some practical issues on loose wires-firstly, it shows end of lifetime of the entire rope, independently of wear, lubrication or wrong winding on the drums or through pulleys; and, secondly, it can stick in the tight pulley-support gaps and cause deterioration of rope structure up to birdcage formations. Normal rope operation should not generate broken wires, so increasing of their number shows a need for rope installation maintenance. This paper presents a methodology of steel rope diagnostics and the results of analysis using multi-criteria analysis methods. The experimental part of the research was performed using an original test bench to detect broken wires on the rope surface by its vibrations. Diagnostics was performed in the range of frequencies from 60 to 560 Hz with a pitch of 50 Hz. The obtained amplitudes of the broken rope wire vibrations, different from the entire rope surface vibration parameters, was the significant outcome. Later analysis of the obtained experimental results revealed the most significant values of the diagnostic parameters. The evaluation of the power of the diagnostics was implemented by using multi-criteria decision-making (MCDM) methods. Various decision-making methods are necessary due to unknown efficiencies with respect to the physical phenomena of the evaluated processes. The significance of the methods was evaluated using objective methods from the structure of the presented data. Some of these methods were proposed by authors of this paper. Implementation of MCDM in diagnostic data analysis and definition of the diagnostic parameters significance offers meaningful results.
“…Safety component device of cylindrical tube as energy absorbers in automobile/train application. 111,112 Figure 23. Application of energy absorption tubes in aircraft fuselage.…”
Section: State-of-the-artmentioning
confidence: 99%
“…Nanofilled composites into energy absorption tube or crash box can be utilized and designed for a particular type of load into the various major structure for high-performance application and safety equipment in major transportation industries such as aerospace, automotive, and marine industry, Figures 22 and 23.Figure 22.Safety component device of cylindrical tube as energy absorbers in automobile/train application. 111,112 Figure 23.Application of energy absorption tubes in aircraft fuselage. 64,113 …”
Glass reinforced epoxy composite tubes filled with 1, 2, 3, and 4 wt. % of HNC, MC, Al2O3, SiO2, and SiC nanofillers were fabricated using wet-wrapping process by hand lay-up and tested under quasi-static axial loadings. Crashworthiness parameters and failure modes were recorded. Results indicated that EAC and the specimens’ failure modes are dominated by the type and wt. % of the embedded nanofillers. As compared to pristine glass/epoxy tubes, an enhancement of 230.42, 243.30, 286.43, and 336.12% in the absorbed energy ( U) was attained by the addition of 1, 2, 3, and 4 wt. % of HNC, respectively. An improvement of 21.93, 87.35, 225.99, and 318.07% in U was achieved by the inclusion of 1, 2, 3, and 4 wt. % of MC, respectively. An enhancement of 17.66, 51.63, and 71.94% in U was reported by the integration of 1, 2, and 3% of nano-Al2O3. Whilst a reduction of 31.16% was noticed for 4 wt. % of nano-Al2O3. The incorporation of nano-SiO2 and nano-SiC exhibits a reduction in U of the fabricated tubes. Composites filled with 4 wt. % of HNC has the highest load carrying capacity and EAC of 32.75 kN and 1110.84 J, respectively. So, they seem to be the best appropriate choice for energy absorbing elements. Glass/epoxy composite tubes filled with HNC, MC, and Al2O3 show outstanding energy absorption characteristics. However, specimens filled with SiO2 and SiC nanofillers are ineffective in the crashworthiness applications.
“…), 6,7 multi-cell configurations 8–11 and longitudinal geometries (i.e. conical, s-shaped structures, corrugated structures and tubes with functionally graded thickness) 12–23 have been investigated in the past years to improve their crushing capacity.…”
This paper evaluates the crashworthiness performance of concentric structures with different numbers of tubes (i.e. one to five) and cross-sectional shapes (i.e. hexagon, octagon, decagon and circle) under the multiple loadings of θ = 0, 10, 20 and 30°. An experimentally validated finite element model generated in LS-DYNA is employed to calculate the crashworthiness parameters including the specific energy absorption, maximum crush force and crush force efficiency. A total of 20 concentric structures are analyzed to explore the effects of number of tubes and cross-sectional shapes on the crushing performance. A multi-criteria decision-making method known as TOPSIS is also used to compare and rank the concentric structures in terms of crushing performance. Based on the results, the hexagonal structure including two tubes and octagonal, decagonal and circular structures including three tubes demonstrate the best results among their corresponding cross-sectional shapes. These structures show 9, 39, 38 and 39% higher specific energy absorption compared to their corresponding single tubal cases, respectively. However, in comparison to single tubal cases, they generate 4, 57, 57 and 58% higher maximum crush force, respectively. As such, the values for the improvement of the crush force efficiency are 3, 26, 25 and 21%, respectively. Furthermore, the decagonal structure including three tubes provides the highest energy absorbing characteristics as compared with all the other structures studied in this research. Meanwhile, taking into account all the multiple loading conditions, this structure shows 50% higher specific energy absorption than the hexagonal structure including single tube (as the weakest structure).
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